1. Field of the Invention
The present invention relates to a wastewater treatment apparatus, a wastewater treatment method, and a wastewater treatment system that control an aeration amount in an aerobic tank, and a control device, a control method, and a program stored in a non-transitory computer-readable recording medium.
2. Description of the Related Art
Conventionally, as a sewage treatment system that treats sewage such as household wastewater or industrial wastewater, various sewage treatment systems using a standard activated sludge method or using a trickling filter method have been put to practical use.
In the sewage treatment system using the standard activated sludge method, aeration treatment is performed to supply oxygen to various kinds of aerobic microorganisms present in a reaction tank, while causing sewage to be treated to flow into the reaction tank. Accordingly, organic matter contained in the sewage in the reaction tank is decomposed by an action of the aerobic microorganisms, thereby enabling to obtain stable quality of treated water.
In the aeration treatment in the reaction tank, influent proportional control, DO (dissolved oxygen) control, or ammonia control is executed with respect to an air diffuser that performs aeration (see Japanese Patent Application Laid-open Publication No. 2005-199116). The influent proportional control uses a flowmeter installed on an inflow side of the reaction tank, to supply air to the air diffuser in an amount proportional to an amount of influent flowing into the reaction tank. The DO control uses a dissolved oxygen analyzer (DO analyzer) installed at a terminal on an outflow side of the reaction tank to measure a dissolved oxygen concentration, and supplies air to the air diffuser so that the dissolved oxygen concentration is maintained at a predetermined concentration. The ammonia control uses an ammonia meter installed at the terminal on the outflow side of the reaction tank to supply air to the air diffuser so that ammonia nitrogen (NH4—N) at the terminal of the reaction tank is maintained at a predetermined concentration.